Plastic Flanged Containers and Food Product Pack Comprising Such Containers

ABSTRACT

Disclosed is a flanged container for a food, in particular a dairy product composition. The container is provided with a hollow body and an annular flange that comprises an inner edge defining a circular upper opening of the container and outer straight side edges. The flange has at least two first flange portions, each defining one of said side edges, two of the side edges having a length I shorter than half of an inner diameter D int  of the opening. Two of the first flange portions are adjacent. At least two second flange portions are provided to each define a corner of the flange, the second flange portions each comprising an outer convex edge extending between two adjacent of said outer straight side edges. A pack comprising the containers is also disclosed.

FIELD OF THE INVENTION

The present invention generally relates to containers used in food packaging industry, particularly to thermoformed plastic flanged containers, such as yoghurt pots or similar. The invention also concerns a pack comprising such flanged containers.

More particularly, the invention relates to a container for a food composition, in particular a dairy product composition, comprising:

-   -   a thermoplastic hollow body comprising a generally planar bottom         and a side wall extending along a longitudinal axis from said         bottom as far as a top, and     -   a generally planar annular flange integral with the body and         connected to the top of the body, the flange comprising an upper         face, a lower face, an inner edge defining a generally circular         upper opening of the container and outer straight side edges,         the outer straight side edges comprising two parallel outer         straight side edges and at least one outer straight side edge         perpendicular to the two parallel outer straight side edges.

BACKGROUND OF THE INVENTION

It is known to produce such a container, and in particular a yoghurt pot or similar, by means thermoforming a sheet of plastic to form the volume. Typically, the plastic sheet is heated and then drawn into a cavity such as by vacuum and/or pressure. As the sheet is drawn into the cavity, the thickness of the portion of the sheet drawn into the cavity is reduced as the sheet material is stretched into the cavity. With such a method, the side wall of the body is thin, while the flange has the same thickness and the same rigidity as the original sheet of plastic.

The plastic containers are conventionally sealed with membranes and can be manufactured and sold in a multiple portion packaging tray comprising an array of separable containers. The containers are generally arranged in layers of four, six or height pots, the containers being connected to one another along their flanges. The French patent FR 2 432 975 describes a pack of plastic flanged containers, in which an individual container may be removed by tearing a separation region provided between two adjacent flanges. After separation, each container flange still has four outer side edges so as to keep integrity of the content. These containers work well when made of relatively brittle plastic. Use of less brittle or more pliable polymers makes the containers more difficult to break apart. Such a difficulty may cause escape of the content when breaking other parts of the container.

In food packaging industry, the plastic containers can be stacked on top of one another so as to form stacks which can be layered on a pallet. A loading weight on a pallet may be much more than 500 kg. Such stacks allow the packaging items at the bottom to withstand the compressive load of the packaging items on top. The plastic containers layers are typically stored in cardboard trays each having a bottom and side walls preventing lateral tilting of the layers.

There are already some solutions to provide to the consumers containers with less plastic material. For instance, the French patent FR 2 432 975 describes plastic containers with polygonal flanges, V-cuts being provided to recycle material of the flanges.

However, the weight of the plastic containers cannot be easily reduced since the containers made of relatively brittle plastic have to be transported in a safe manner and without any deformation. The packs of containers have to be sufficiently robust in particular for transportation on a pallet. It is also preferably required that the containers are user-friendly, i.e. not complicating user's operations such as separating an individual container, opening the membrane seal, eating the content.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide flanged containers using less plastic material and addressing one or more of the above mentioned problems.

To this end, embodiments of the present invention provide a container of the above mentioned type, characterized in that the flange comprises:

-   -   at least two first flange portions, each defining one of said         outer straight side edges, at least two of the straight side         edges being shorter than half of an inner diameter of said upper         circular opening, two of the first flange portions being         adjacent first flange portions, and     -   at least two second flange portions that each defines a corner         of the flange, at least one of the second flange portions         comprising an outer convex edge extending between two adjacent         of said outer straight side edges.

Advantageously, the size of outer straight side edges of the flange is reduced, thus allowing a higher reduction of material in the corners. Surprisingly, the flanged containers can be efficiently connected to one another along their first flange portions, without accidental separation, even when using brittle plastic material (for instance polystyrene rather than polyethylene or polypropylene). Outer convex edges longer than the outer straight edges make also the flange user-friendly and easy to manipulate when removing the membrane seal.

Furthermore, use of a body having a circular opening allows a good compromise for accessibility to the content without increasing radial dimension(s) of the container.

According to a particular feature, the first flange portions comprise at least three first flange portions, each having a continuous cut out line defining one of said outer straight side edges, each of the outer straight side edges having a length shorter than half of said inner diameter of the upper circular opening, and each of said second flange portions comprises an outer convex edge that extends between two adjacent of said outer straight side edges. With such an arrangement, container material is saved and a layer of containers can be easily stored in a stackable tray (having a parallelepiped configuration).

According to a particular feature, the opening is circular and has an inner diameter D_(int), any one of said outer straight side edges having a length l that satisfies the relation:

l/D _(int)<0.45.

Of course, length of each the first flange portions is equal to the length l of the corresponding outer straight side edge. This length is not necessarily the same for the different first flange portions. In one embodiment, the above ratio is preferably inferior to 0.4. Accordingly, savings of a material is obtained. Preferably, four first flange portions are provided on the flange, the four corresponding outer straight side edges defining a virtual square, each of the outer straight side edges having the same length.

According to a particular feature, each of the outer straight side edges has a length l equal to about one third of the length of one side of said virtual square. With such an arrangement, a particularly soft transition is obtained between the short straight side edge and the outer curved edge forming the corner of the container, while increasing removal of material in the corner as compared to conventional flanges.

According to a particular feature, the flange has a geometrical shape, wherein the longitudinal axis forms an intersection between:

-   -   a first median plane dividing the flange into two symmetrical         halves; and     -   a second median plane, preferably perpendicular to the first         median plane, dividing the flange into a first C-shaped portion         and a second C-shaped portion, the second C-shaped portion being         of lighter weight than the first C-shaped portion;         and wherein the ratio between the maximal radial extension of         the first C-shaped portion and the inner diameter of said         opening is comprised between 0.18 and 0.22, the ratio between         the maximal radial extension of the second C-shape portion and         the inner diameter of said opening being comprised between 0.15         and 0.18.

With such a specific geometry, there is provided a C-shape portion (the first one) more attractive for the removal of the membrane seal or similar closure means, while the other C-shape portion (the first one) is optimized for lowering weight of the container. Symmetry of the first C-shape portion is also advantageous for a better manipulation by a left-handed person.

In various embodiments of the flanged container of the invention, recourse may optionally also be had to one or more of the following dispositions:

-   -   the first C-shape portion is inscribed in a first virtual         isosceles right triangle having its long side contained in the         second median plane and the second C-shape portion is inscribed         in a second virtual isosceles right triangle having its long         side contained in the second median plane, wherein the following         relation is satisfied:

⅔*D _(int) ≦c≦¾*D _(int),

where b is the length of the small side of the first virtual isosceles right triangle, c is the length of the small side of the second virtual isosceles right triangle and D_(int) the inner diameter of said opening;

-   -   two of the second flange portions each define an external         perimeter portion corresponding to at least 1/7 of the external         perimeter defined by the flange;     -   two of the second flange portions have rounded outer side edges         that form circular segments arranged coaxially with the circular         opening;     -   the body has a circular section in cross-section and extends         symmetrically around said longitudinal axis, the bottom having a         periphery of circular shape;     -   the body comprises a side wall having a generally cylindrical         upper portion, possibly covered by a decorative strip, and a         lower portion tapering from the upper portion toward the bottom;     -   the container comprises a membrane seal that is fixed only to         the upper face of the flange, the membrane seal sealing the         opening and covering entirely said upper face of the flange.

A further purpose of the invention is to provide a food pack easy to be manipulated in a supermarket (before exposure of the containers by the operators and thereafter by the final consumer) and resistant while reducing amount of plastic material.

To this end, embodiments of the present invention provide a food pack comprising a plurality of containers according to the invention arranged in at least one row, and preferably at least four containers arranged in two rows, the flanges of the pack being integrally formed and separably joined to each other at a junction between two of the first flange portions of two distinct containers of the pack.

Accordingly, there is provided a pack, which is particularly well adapted for transportation in a stackable tray, while limiting the amount of material.

Two of the second flange portions may be advantageously rounded and define external portions of the pack. These two second flange portions are adjacent corner portions separated by one of the first flange portions. This geometry is user-friendly (without sharp edges).

According to a particular feature, the pack comprises a group of four containers provided with a star-cut pattern between the individual containers, said star-cut pattern having a length L1, such that the following relation is observed:

0.75≦L1/D _(int)≦0.95.

Accordingly, the material saved by the larger cut at the central region may be re-used for other packs, for example by recycling. It should be noted that the flanges may have a constant thickness, this thickness being provided at the junction. Here, tearing the separation region for removal of an individual container is not facilitated by a reduction of thickness, the shorter length of the outer straight side edges being sufficient to make the removal easy for the user.

It is also provided, according to the invention, a use of a container according to the invention for containing a dairy product, preferably a yoghurt composition having a weight not inferior to 50 g and not superior to 500 g, preferably not inferior to 75 or 80 g and not superior to 400 g, and more preferably not inferior to 100 g and not superior to 200 g. A yoghurt composition having a weight comprised between 100 and 200 g is highly preferred. The shape of the opening and the flange are particularly user-friendly while the arrangement of the body is very compact when containing a yoghurt composition or similar dairy product having a weight comprised between 100 and 150 g, preferably about 125 g.

Other features and advantages of the invention will become apparent to those skilled in the art during the description which will follow, given by way of a non-limiting example, with reference to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of food pack according to a first preferred embodiment of the invention, the containers of the pack being not provided with their membrane seal or similar closure element;

FIG. 2 is perspective view showing an individual container according to a second preferred embodiment of the invention the invention;

FIG. 3 is a side view of the container shown in FIG. 2;

FIG. 4 is schematic view showing a stackable tray and arrays of containers according to the second embodiment of the invention to be transported in the tray;

FIGS. 5 a and 5 b show the same top view of a container without the membrane seal;

FIG. 6 is a view of the bottom of the embodiment shown in FIG. 1;

FIG. 7 is a close-up view of the embodiment shown in FIG. 1;

FIG. 8 is a top view of a plastic sheet showing the cut suitable for obtaining a plurality of containers according to the first embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

In the various figures, the same references are used to designate identical or similar elements.

FIG. 1 shows a food pack 1 comprising for instance four individual containers 2. Of course the number of containers 2 may vary and a number of 2, 6, 8, 10 or 12 containers 2 may be provided, in a non-limitative example. The containers 2 are arranged in at least one row, and preferably at least in two rows 3, 4 when the pack 1 comprises four or more containers 2.

Referring to FIGS. 1, 2 and 3, the containers 2 are preferably polystyrene containers, each comprising a hollow body 5 having a side wall extending along a longitudinal axis X from a bottom 6 as far as an open top 7. The side wall 5 a of the body 5 is tubular and is adapted to be covered by a cylindrical decorative strip St, sticker or banderol in the upper area A adjacent to the upper body opening, called hereafter circular opening 8. It is understood that the longitudinal axis X is here a central axis for the body 5 and the opening 8. Fixing of the strip St is performed in a known manner. In a first embodiment as shown in FIG. 6 in particular, the bottom 6 may be planar. In the second embodiment as shown in FIGS. 2-3, the bottom 6 may be provided with a recess or cavity 6 a with a concavity oriented to the exterior. The annular portion 6 b of the bottom 6, defined around the cavity 6 a, has a diameter Db inferior to the diameter D_(int) of the circular opening 8 defined at the top 7 of the body 5. The diameter Da of the cavity 6 a may be comprised between one half and two thirds of the diameter D_(int) of the circular opening 8.

The bottom 6 provided with the cavity 6 a has a better strength for better supporting a compression load.

Of course, the bottom 6 may still be considered as a generally planar bottom, at least because the bottom 6 has a flat shape and the container 2 is adapted to be maintained vertically when the bottom 6 is in contact with a horizontal base support (the longitudinal axis X being vertical). Of course, the height of the cavity 6 a is preferably very small, for instance about 0.5 mm.

Referring to FIG. 3, the polystyrene used in the container 2 has a thickness e of about 0.2 mm in the body 5 and a thickness E of about 0.85 mm in the flange 10. The thickness may vary depending upon the food packaging application and may be inferior to 1 mm and superior to 0.7 mm (the range 0.8-0.9 mm being preferred). Thicker materials may be used for heavier food products. A film called thereafter a membrane seal S is used to cover the containers 2. Such a membrane seal S may be a plastic film made from plastic resin or a foil film. An adhesive may be used to seal the film to the upper face 10 b of the flange 10. The membrane seal S entirely covers this upper face 10 b.

Referring to FIGS. 1-3 and 6, each container 2 comprises a generally planar annular flange 10 integral with the body 5 and connected to the top 7 of the body 5. The flange 10 comprises a lower face 10 a, an upper face 10 b, an inner edge 10 c delimiting the generally circular opening 8 of the container 2, and three or four outer straight side edges 11 a, 11 b, 11 c, 11 d. The outer straight side edges 11 a, 11 b, 11 c, 11 d are rectilinear edges defined by respective first flange portions 12. The adhesive for the membrane seal S is preferably in contact with the upper face 10 b at a distance of the inner edge 10 c and at a distance of the outer straight side edges 11 a, 11 b, 11 c, 11 d.

In the exemplary embodiment shown in FIG. 1, the first flange portions 12 form the four sides of the flange 10. Four second flange portions 14, 15 are provided to form complementary corner portions relative to the first flange portions 12. Each of the second flange portions 14, 15 thus separates two adjacent first flange portions 12. In the exemplary embodiments shown in the figures, the two adjacent first flange portions 12 extend according perpendicular directions (these directions being of course defined by the corresponding outer straight side edge 11 a, 11 b, 11 c, 11 d).

Preferably, the second flange portions 14, 15 have curved and/or rounded outer side edges, two of which (outer side edges 14 a as shown in FIG. 2) form circular segments arranged coaxially with the circular opening 8. More generally, the second flange portions 14, 15 each have an outer convex edge obtained by cutting material in corners of a raw plastic rectangular matrix. Each of the outer straight side edges 11 a, 11 b, 11 c, 11 d are shorter than half of the inner diameter D_(int) of the circular opening 8, thus permitting to remove more plastic material in the corners of the matrix. For instance, the ratio l/Dint satisfies the relation:

l/D _(int)<0.45,

where l is length of any one of the first flange portions 12 and D_(int) is the inner diameter of said circular opening 8. The ratio i/Dint may also be inferior to 0.4 in one particular embodiment. With this arrangement, the change of direction between the straight direction defined by the first flange portion 12 and the tangent direction of the adjacent second flange portion 14 or 15 is minimized (at the corresponding end of the first flange portion 12). The soft transition may prevent a sharp protrusion from forming when the flanges 10 are cut. The perimeter of the flange 10 of an individual container 2 is free of serrated surfaces in one embodiment.

Referring to the preferred embodiment of FIG. 5 a, the container 2 is cut from a squared matrix made of polystyrene or similar thermoplastic material. Accordingly, the four outer straight side edges 11 a, 11 b, 11 c, 11 d define a virtual square 16, each of the outer straight side edges 11 a, 11 b, 11 c, 11 d having the same length 1. As shown in FIG. 5 a, this length l may be equal to about one third of the length L of one side of the virtual square 16 (i.e. one third of the side of the squared matrix). Although the same length l is shown in FIG. 5 a, it should be comprised that this length may vary depending on the sides of the flange 10. For instance, one of the outer straight side edges may be a bit shorter or longer than one or more of the other outer straight side edges.

Referring to FIGS. 1 and 5 a-5 b, the flange 10 may extend around the longitudinal axis X with such a geometrical shape that this longitudinal axis X forms an intersection between:

-   -   a first median plane P1 dividing the flange 10 into two         symmetrical halves M1, M2; and     -   a second median plane P2 perpendicular to the first median plane         P1 and dividing the flange 10 into a first C-shaped portion 17 a         and a second C-shaped portion 17 b.

The second C-shaped portion 17 b as shown in the left part of the FIGS. 5 a-5 b comprises the two second flange portions 14 that form circular segments. The first C-shaped portion 17 b as shown in the right part of the FIGS. 5 a-5 b comprises the two other second flange portions 15. As the radial extension of these second flange portions is higher, they are especially adapted for manual removal of the membrane seal S. The second C-shaped portion 17 b is thus of lighter weight than the first C-shaped portion 17 a. In one less preferred embodiment of the flange 10, the first and second median planes P1, P2 could be not perpendicular (forming for instance an angle of about 45°).

In one non-limitative embodiment, the ratio between the maximal radial extension e1 of the first C-shaped portion 17 a and the inner diameter D_(int) of the circular opening 8 is comprised between 0.18 and 0.22, while the ratio between the maximal radial extension e2 of the second C-shape portion, 17 b and the inner diameter D_(int) is comprised between 0.15 and 0.18. Accordingly, the radial extension of the flange remains much lower than one quarter of the inner diameter D_(int), thus allowing saving much more plastic material. More generally, the second flange portions 14, 15 have a maximal radial extension longer than the radial extension of the first flange portions 12. With the maximal radial extension e1 provided at the second flange portion 15, the corresponding angle is well adapted for a handling and an adequate pulling of the membrane seal S by the user's hand. As shown in the non-limitative example of FIGS. 5A-5B, the first C-shaped portion 17 a allows a better/faster manipulation by the user (left-handed or right-handed user) because two similar or identical second flange portions 15 are provided with such a maximal radial extension e1.

In one alternative embodiment, three of the second flange portions could be rounded to form circular segments, so as to remove more plastic material. In such a case, only one of the second flange portions has a higher maximal radial extension e2, with the same shape as in the ends of the first C-shaped portion 17 a.

Now referring to FIG. 5 b, the first C-shape portion 17 a is inscribed in a first virtual isosceles right triangle T1 having its long side contained in the second median plane P2. Similarly, the second C-shape portion 17B is inscribed in a second virtual isosceles right triangle T2 having its long side contained in the second median plane P2. The following relation is satisfied:

⅔*D _(int) ≦b≦c≦¾*D _(int),

where b is the length of the small side of the first virtual isosceles right triangle T1, c is the length of the small side of the second virtual isosceles right triangle T2 and D_(int) the inner diameter of the circular opening 8.

With such a flange 10 provided with the circular opening 8, a good compromise is obtained between savings of material, size of the diameter D_(int) for an easy access to the content, and facility to remove the membrane seal S. Furthermore, with a short junction J, the containers 2 can be separated without forming any sharp corner or hook in the corners, large curved edges being defined by the second flange portions 14 and 15. Preferably, the angle defined between the direction defined by one of the outer straight side edges and the tangent direction of the adjacent second flange portion 15 of the first C-shaped portion 17 b is about 10° and not superior to 15°.

It should be also noted that the radial extension of the flange 10 is not a parameter easy to reduce, at least because essential functions of the flanges 10 in a pack 1 include:

-   -   increasing strength for supporting a compression load; and     -   preventing a contact between the container bodies 5 to occur, in         particular when the containers 2 are transported in a stackable         tray T as shown in FIG. 4.

As shown in FIG. 4, when arranged in a tray T, each pack 1 of the containers 2 is arranged inside the interior volume V defined by the tray T. The side walls 18 of the tray T may have a height h equal or slightly superior to the height H of the containers 2. The side walls 18 are in contact with some of the outer straight side edges 11 a, 11 b, 11 c, 11 d of the pack 1. As shown in FIG. 1, the other outer straight side edges 11 a, 11 c 11 c, 11 d may be each arranged adjacent to one end of a star-cut pattern 20 when the pack 1 comprises at least two rows 3,4.

As shown in FIG. 1, the containers 2 are separably joined to each other at a junction J of two first flange portions 12 of two distinct containers 2 of the pack 1. Here, the second flange portions 14 that are rounded define external portions of the pack 1. These second flange portions 14 define corners that do not have straight edges or sharp corners. In the pack 1 shown in FIG. 1, the star star-cut pattern 20 a is defined between four containers 2 of a group of containers arranged in as squared manner. The star-cut pattern 20 is thus defined by four edges.

Referring to FIG. 7, each of these edges comprises a curved edge portion 21 extending between two straight edges 20 a, 20 b. The respective ends of the corresponding second flange portion 15 form the straight edges 20 a, 20 b. The angle a defined between two adjacent straight edges 20 a is here comprised between, 15 and 30°, and preferably equal to about 20°. The angle β defined between the two other adjacent straight edges 20 b is also comprised between, 15 and 30°, and preferably equal to about 20°. Here, the angle α and the angle β are the same but in one alternative embodiment, the flange 10 could be asymmetrically shaped. For instance, the flange 10 could have one of the second flange portions 15 provided with a more rounded edge 20 b, such that the angle β is superior to the angle α.

As shown in FIGS. 1 and 7, the star-cut pattern 20 between the individual containers 2 may have a length L1 much superior to the length l of the outer straight side edges 11 a, 11 b, 11 c, 11 d. Referring to FIG. 2, the thickness E of the flange 10 may be constant and such thickness E is for example not decreased at the junctions J. Preferably, the following relation is satisfied:

0.75<L1/D _(int)<0.95

With such a configuration and a sufficient thickness E at the junctions J, the containers 2 of a pack 1 cannot be accidentally separated. Furthermore, two and preferably all the second flange portions 14, 15 may each define an external perimeter portion corresponding to at least 1/7 of the external perimeter defined by the flange 20. Preferably, for an individual container 2 separated from a four containers pack 1 as shown in FIG. 1, the two outer straight side edges 11 b, 11C that are obtained after a tearing at the corresponding junctions J represent one fifth or less of the outer perimeter of the flange 10.

Referring to FIG. 2, the body 5 preferably has a circular section in cross-section and extends symmetrically around the longitudinal axis X. With such a circular section, an operation using a spoon for retrieving the whole content is easier. The lower portion of the side wall 5 a may also be tapered toward the bottom 6 for the same purpose. A brand name or a similar pattern could be marked in this lower portion 32 when forming the body 5. With this arrangement, the height of the upper portion 30 defining the upper area A for the decorative strip St is advantageously reduced, thus saving packaging material. Moreover, integration of the decorative strip St is better when combining a circular cross section of the body 5 and such a tapered lower portion 32. In contrast, with a shorter decorative strip St partially covering a conventional tubular wall extending from the flange to the bottom with a substantially constant cross-section, the final consumer will immediately think that the decorative strip St has not the expected size. As a result, this could be interpreted as a problem with the packaging and the consumer could be dissuaded to buy the product. More generally, the body 5 may be covered by any kind of decorative strip St adapted to be shaped according an annular form, preferably a cylindrical form. In one embodiment the body 5 is partially covered by a sticker.

The containers 2 are intended to be filled with a liquid or semi-liquid dairy product or similar food, preferably a yoghurt composition. The containers 2 can be used for 50-500 g capacity, preferably 75-200 g capacity. Of course, the containers 2 of the present invention are not in any way limited to yoghurt but can be intended to contain all sorts of liquid, semi-liquid or flowable edible products. A container 2 adapted to receive 125 g of a yoghurt composition or similar may be provided with a flange 10 having a diameter of the circular opening equal to about 53-54 mm, while the length L of the flange 10 (i.e. the distance between two parallel outer straight side edges) is equal to about 63 mm and the height H of the container 2 may be equal to about 66-67 mm. The length l of each of the four outer straight side edges 11 a, 11 b, 11 c, 11 d may be equal to about 21 mm or less.

Referring to the non-limitative embodiment of FIG. 8, a group of twenty-four containers 2 is obtained, starting from a rectangular sheet Sh having a length Ls equal or slightly higher than 6*L (L being length of the squared matrix for each individual container 2) and a width is substantially equal to 4*L. The thickness of the sheet Sh is the same as the thickness E of the flanges 10. Of course, margins 35 of the sheet Sh may be reduced if desired. Such margins 35 are required for maintaining the sheet Sh in a determined position.

Before the cut, the sheet Sh may be punched to form the body cavities that are filled with the food (typically a dairy product composition). The cut is performed after closing the cavities using a foil that is suitable for food contact.

In this example, the surfaces cut according to the star-cut pattern 20 represent about 3-4% and preferably about 3.3% of the whole surface of the sheet Sh. The surfaces 34 cut to delimit the outer side edges 14 a represent between 5 and 7% of the whole surface of the sheet Sh, preferably 6%. Accordingly, the useful surface of the sheet Sh for producing the twenty-four containers 2 may be inferior to 90% and preferably inferior to 85% of the whole surface of the plastic sheet Sh (including margins 35 that represent less than 8%, and preferably less that 7% of the whole surface). Containers 2 shown in FIGS. 1-6 may be obtained by using such a sheet Sh. As a result, 10% or respectively 15% of plastic material can be saved and used for an improved recycling. Density of the plastic sheet Sh before forming operation is preferably inferior to 0.9, for instance about 0.85 for polystyrene.

The present invention has been described in connection with the preferred embodiments. These embodiments, however, are merely for example and the invention is not restricted thereto. It will be understood by those skilled in the art that other variations and modifications can easily be made within the scope of the invention as defined by the appended claims, thus it is only intended that the present invention be limited by the following claims.

Any reference sign in the following claims should not be construed as limiting the claim. It will be obvious that the use of the verb “to comprise” and its conjugations does not exclude the presence of any other elements besides those defined in any claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. 

1. A container for a food composition, comprising: a thermoplastic hollow body comprising a bottom and a side wall extending along a longitudinal axis from said bottom as far as a top, and a planar annular flange integral with the body and connected to the top of the body, the flange comprising a lower face, an upper face, an inner edge defining a circular upper opening of the container and outer straight side edges, the outer straight side edges comprising two parallel outer straight side edges and at least one outer straight side edge perpendicular to the two parallel outer straight side edges, characterized in that the flange comprises: at least two first flange portions, each having a continuous cut out line defining one of said outer straight side edges, at least two of the outer straight side edges having a length l shorter than half of an inner diameter D_(int) of said circular upper opening, two of the first flange portions being adjacent first flange portions, and at least two second flange portions that each defines a corner of the flange, at least one of said second flange portions comprising an outer convex edge that extends between two adjacent of said outer straight side edges.
 2. The container according to claim 1, wherein: said first flange portions comprise at least three first flange portions, each having a continuous cut out line defining one of said outer straight side edges, each of the outer straight side edges having a length l shorter than half of an inner diameter D_(int) of said upper circular opening, and each of said second flange portions comprises an outer convex edge that extends between two adjacent of said outer straight side edges.
 3. The container according to claim 2, wherein the circular opening has an inner diameter D_(int), and wherein any one of said outer straight side edges has a length I satisfying the relation: I/D _(int)<0.45.
 4. The container according to claim 1, wherein when four of said first flange portions are provided on the flange, four corresponding outer straight side edges are provided and define a virtual square.
 5. The container according to claim 34, wherein each of the outer straight side edges has the same length l.
 6. The container according to claim 5, wherein each of said outer straight side edges has a length equal to about one third of the length of one side of said virtual square.
 7. The container according to claim 1, wherein the flange has a geometrical shape, wherein said longitudinal axis forms an intersection between: a first median plane dividing the flange into two halves; and a second median plane dividing the flange into a first C-shaped portion and a second C-shaped portion, the second C-shaped portion being of lighter weight than the first C-shaped portion.
 8. The container according to claim 7, wherein the second median plane is perpendicular to the first median plane and the second C-shaped portion is inscribed in a virtual isosceles right triangle having its long side contained in the second median plane.
 9. The container according to claim 8, wherein the first C-shaped portion has a first maximal radial extension and the second C-shaped portion has a second the maximal radial extension, and wherein the ratio between the first maximal radial extension and the inner diameter D_(int) of said opening is comprised between 0.18 and 0.22, the ratio between the second maximal radial extension and the inner diameter D_(int) of said opening being comprised between 0.15 and 0.18.
 10. The container according to claim 7, wherein the first C-shaped portion is inscribed in a first virtual isosceles right triangle having its long side contained in the second median plane and the second C-shaped portion is inscribed in a second virtual isosceles right triangle having its long side contained in the second median plane, wherein the following relation is satisfied: ⅔*D _(int) ≦b≦c≦¾*D _(int), where b is the length of the small side of the second virtual isosceles right triangle, c is the length of the small side of the first virtual isosceles right triangle and D_(int) the inner diameter of said opening.
 11. The container according to claim 4, wherein two of the second flange portions define each an external perimeter portion corresponding to at least 1/7 of the external perimeter defined by the flange.
 12. The container according to claim 4, wherein two of the second flange portions have rounded outer side edges that form circular segments arranged coaxially with the circular opening.
 13. The container according to claim 4, wherein the body has a circular section in cross-section and extends symmetrically around said longitudinal axis, the bottom having a periphery of circular shape.
 14. The container according to claim 1, wherein the body comprises a side wall having a generally cylindrical upper portion and a lower portion tapering from the upper portion toward the bottom.
 15. The container according to claim 4, comprising a membrane seal that is fixed only to the upper face of the flange, the membrane seal sealing the opening and covering entirely said upper face of the flange.
 16. A food pack comprising a plurality of containers such as defined in of claim 1, wherein said containers are arranged in at least one row.
 17. The pack according to claim 16, comprising at least four containers arranged in two rows, said flanges of each of said containers of the pack being integrally formed and separably joined to each other at a junction of two first flange portions of two distinct containers of the pack.
 18. The pack according to claim 16, wherein two of the second flange portions are rounded and define external portions of the pack.
 19. The pack according to claim 16, comprising a group of four containers provided with a star-cut pattern between the individual containers, said star-cut pattern having a length L1, such that the following relation is satisfied:
 0. 75≦L1/D _(int)≦0.95.
 20. The pack according to claim 16, wherein the flanges have a determined constant thickness, said junction having the determined thickness.
 21. (canceled)
 22. A packaged food product comprising 50 g to 500 g of a yoghurt composition within a container of claim
 1. 